The present invention is directed to devices for yarn winding and, more particularly, to devices for co-winding a carrier yarn together with an insert yarn to form a two-ply yarn.
Automatic winders are widely used for winding yarn from spinning bobbins onto packages of predetermined yarn quantity and shape. A winder usually has a bobbin holder for housing several spinning bobbins. In a typical configuration, the yarn on the spinning bobbin is fed to a predetermined position on the winder where it is pulled upward in the axial direction of the bobbin. The yarn is taken up to a package while being traversed by a traversing device. Examples of automatic winders are described in U.S. Pat. No. 5,056,734 to Uchida et al. and U.S. Pat. No. 4,805,846 to Ueda et al. Other examples of automatic winders include those manufactured by W. Schlafhorst AG and Co., such as the winder described in U.S. Pat. No. 5,605,296 to Haasen et al. and the combined textile yarn spinning and winding system disclosed in U.S. Pat. No. 5,179,829 to Grecksch et al.
Multi-bobbin automatic winders usually are equipped with an automatic doffing feature. As yarn is being unwound from one of the bobbins, the yarn ends from the other bobbins are held by a holding means. When the yarn being unwound from the bobbin expires, one of the awaiting yarn ends is engaged and fed to a splicing mechanism. The end of the yarn from the expired bobbin is spliced with the leading end of the yarn from the fresh bobbin, after which time normal winding resumes. An example of a splicing mechanism for an automatic winder is described in U.S. Pat. No. Re 31,594 to Mima, the disclosure of which is incorporated by reference.
In many applications, it is desirable to co-wind a base yarn with another yarn to form a two-ply yarn. When preparing yarns for use in carpets, for example, a low-melt binder fiber often is inserted into a base fiber prior to winding. Examples of base fibers commonly used in carpets include polyesters, nylon-6, and nylon-6,6. Examples of binder fibers commonly used include co-polyamides as described in WO 99/14408 A1 and EP 324,773 B1. When the two-ply yarn is exposed to normal twist setting conditions, the binder fiber melts and flows to the points of intersecting base fibers. As the yarn cools, a bond is formed between the base fibers. Carpets made from these types of yarns have improved performance characteristics, particularly wear resistance.
Another common example of a two-ply carpet yarn is one in which a base yarn is co-wound with an electrically conductive filament. The conductive filament helps to reduce static propensity in the carpet. U.S. Pat. No. 4,612,150 to De Howitt shows an example of a low denier, conductive filament. The filament contains a polymeric component and carbon black to provide electrical conductivity. The bi-component filament is prepared as a sheath/core, with the non-conductive component fully encapsulating a conductive core. Other examples of conductive filaments are described in U.S. Pat. No. 4,900,495 to Lin and U.S. Pat. No. 5,277,855 to Blackmon et al.
The presently used technique for preparing two-ply yarns is creel frame insertion, as illustrated in FIG. 1. Creel frame insertion introduces a back-winding step between spinning and winding. The back-winding step is needed to convert the spinning bobbins into larger round bobbins (sometimes referred to as xe2x80x9ccheesexe2x80x9d bobbins). The smaller spinning bobbins are unsuitable for use in creel frame insertion because the high linear velocities, typically on the order of 1,200 m/min, would require operators to replace expired spinning bobbins with fresh bobbins at an impractically high frequency.
The present creel frame insertion technique suffers from several drawbacks. One of the drawbacks is that the creel frame unit is rather bulky and consumes valuable floor space in mills. A principal drawback is the need for the separate back-winding step. The back-winding step increases the overall amount of time needed from spinning to winding, reducing process efficiency. In addition, the creel frame insertion technique requires that the automatic doffing feature on the winders be disabled.
It would be desirable to develop an alternative technique for inserting yarn prior to winding, especially one that eliminates the need for a creel frame and the need for back-winding. It would be particularly desirable to develop an insertion technique that also permits the automatic doffing feature on the winders to be used.
The present invention, according to one aspect, is directed to an insertion mechanism for bringing an insert yarn into association with a base yarn in an automatic winder of the type in which a base yarn is drawn out from a layer of yarn on a spinning bobbin and is rewound onto a package. The insertion mechanism comprises an insertion guide for feeding the insert yarn to a predetermined location, a tensioning device for maintaining tension on the insert yarn, and a mounting bracket adapted to permit attachment of the insertion mechanism to an automatic winder.
Another aspect of the present invention is directed to an automatic winder for drawing out a base yarn from a layer of yarn on a spinning bobbin and rewinding the base yarn onto a package together with an insert yarn. The automatic winder comprises a winding unit operable for drawing out and rewinding a base yarn onto a package together with an insert yarn. The winder has an insertion guide for feeding an insert yarn to a predetermined location of the automatic winder. A tensioning device maintains tension on the insert yarn as it is fed to the predetermined location of the winder.
Yet another aspect of the present invention is directed to a method of rewinding a base yarn from a layer of yarn on a spinning bobbin onto a package together with an insert yarn. An automatic winder having winding unit operable for drawing out and rewinding a base yarn onto a package is provided. An insert yarn is fed to a predetermined location of the automatic winder and into association with the drawn-out base yarn while tension is maintained on the insert yarn. The base yarn and the insert yarn are rewound together onto a package.
The present invention provides an efficient and effective alternative to the creel frame insertion method currently used for preparing two-ply yarns. The insert yarn is conveniently fed directly into the automatic winder used for rewinding the base yarn from the spinning bobbins onto a package, thereby avoiding the need for back-winding the base yarn onto larger bobbins prior to re-winding. The present invention also permits doffing in winders having an automatic doffing feature. Thus, the present invention overcomes several of the drawbacks associated with present techniques used for preparing two-ply yarns for winding.